Flat platelike thermoelectric electricity generating members are available which have an array of heatable thermocouple junctions on one side thereof and a corresponding plurality of coolable thermocouple junctions on the opposite side thereof. However, such thermocouple members are, in general, not directly engageable with hot combination gases, such as in the interiors of fuel fired stoves or the like, nor with cooling air or water, in an efficient and practical manner for electricity generation.
There has been a long felt need throughout the world, particularly in remote, underdeveloped and/or wild geographic areas, where commercial central electric power generating plants are not accessible, for electricity at moderate cost.
Small diesel or gasoline engine powered rotary generators have been found to be less than entirely satisfactory due to their disadvantageous need for special fuel which may be costly or require transportation over large distances, capital cost, difficulty of repair, noise, limited service life due to wearing out of rotating and reciprocating parts, need for sophisticated maintenance skills and incompatibility with local fuel burning devices.
Further, attempts to utilize photovoltaic devices (so-called solar cells) for such electricity generating purposes have also proved to be less than entirely satisfactory. Initial capital cost is high due to the cost of large square footage areas of photovoltaic cells required. Initial capital cost and maintenance costs also tend to be relatively high due to the need for a relatively large storage battery bank, this need being compounded by the fact that even on sunny days only about four hours per day of fully effective photovoltaic generating capability is available and not all of the days of the year will be sunny, even in areas with little annual rainfall. Indeed, in geographic areas with the significant number of overcast or rainy days, or where daylight hours are very short for a significant portion of the year, photovoltaic electric generating systems have appeared to be impractical.
On the other hand, it is estimated that about two-thirds of the world population burns fuel for heating and cooking purposes and this is the case in many of the world's remote, unimproved or wild areas where commercial central electric power plants are not available. It is estimated that a system in accord with the present invention can provide electric power for perhaps one-third or one-half the cost of a photovoltaic system, per watt output, without counting the benefit of water heating, space heating and so forth as an extra output of the present system. For comparable weekly or monthly electric power output, a thermoelectric system in accord with the present invention may require only one-quarter to one-fifth the battery storage, and require a smaller battery charging and regulating device. In particular, apparatus according to the present invention can be operated effectively not merely during the four peak sunlight hours of the day, but for up to 24 hours a day or whenever fuel may be burned by the user for other purposes, such as cooking, building heating, or small scale household, commercial or light industrial purposes. Moreover, the electricity generating apparatus of the present invention is compact and capable of installation in portable heating apparatus, existing on-site heating apparatus, or specially constructed fuel burning devices. Special fuels are not required and whatever is available locally can be utilized.
The need for some electrical generation capability in such remote, etc. areas is clear and long-standing. Electric powered cooling for certain medications and other hospital or medical needs, electric power for radio or telecommunications for remote villages, and remote community lighting are a few examples.
Accordingly, it is an object of this invention to provide a thermoelectric electricity generating system of relatively simple construction, relatively low capital cost, and long operating life, which can be implemented with few or no moving parts, which is suitable to portable or remote use in primitive areas of the world, and which should have a relatively long operating life with little or no maintenance requirement.
It is a further object of the invention to provide a system, as aforesaid, adaptable to local fuel and heating sources with a minimum in the way of tools and skills.
The objects and purposes of the invention include provision of a thermoelectric electricity generating system for connection with a heat source and heat acceptor in the form of a source of fluid at a temperature less than that of the heat source. The system includes first and second platelike thermoelectric members having opposed surface layers of low electrical conductivity but which permit maximum heat transfer across the thickness thereof. A plurality of flat platelike thermoelectric members are spaced edge-by-edge in a recess in at least one of the plates in snugly sandwiched, heat conductive relation with the opposed surface layers of the first and second plates. Thermoelectric members comprise a plurality of heatable junctions and a plurality of coolable junctions respectively in heat conducting relation with the first and second plates, such that the heat source and heat acceptor respectively acting on the first and second plates cause the thermoelectric members to generate electricity.
Other objects and purposes of the invention will be apparent from reading the following specification and inspecting the accompanying drawings.